Unlike a block of Random Access Memory (RAM), which in response to a typical read command returns data stored at a specific address, a block of Content-Addressable Memory (CAM) responds instead to a match command to return the address of the memory location which stores the specific matched data word. This functionality is very useful for some applications, such as high-speed on-chip searching.
A Ternary CAM (TCAM) is a special type of CAM in which “wildcards” or “don't cares” can be stored along with the data. Hence there are three logical states (0, 1 and “X”) and hence the ternary nomenclature. This functionality is suitable for many CAM applications where decisions are applicable to a broad range of data.